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Do These Optical Illusions Have You Fooled?

Can you see the hidden 3D image in the stereogram above? Continue reading and the answer will be revealed…

Optical illusions help us understand how we perceive the world around us and why. Sometimes what we believe we are seeing, isn’t reality. Why does this happen? Our brain works to interpret everything we see, and sometimes shadows, lighting, shapes and other factors mislead that interpretation.

Stereograms

Our depth perception is challenged with stereograms. Finding 3D shapes within a 2-demensional image isn’t easy, but by staring at a repeating pattern in wallpaper, the brain is tricked into matching pairs of them to perceive a virtual plane behind it. This virtual plane is where the hidden image lies. This was discovered by Dr. Bela Julesz in 1959, which helped change the belief by most vision scientists at the time that depth perception solely occurs in the eye. It is now known that depth perception is a neurological process that occurs in the brain.

In order to see the hidden image in a stereogram, you must have two eyes. Those with impaired depth perception or an extremely dominate eye will have more difficulty seeing the image. Bring the stereogram close to your eyes, and then slowly distance yourself from the image while keeping your eyes relaxed. The idea is to keep your eyes relaxed and look just past the wallpaper pattern, as if you are looking through it. It may take some time to train yourself to be able to see hidden images in stereograms. Once you are comfortable with still stereograms, then animated stereograms won’t be any trouble for you at all: As for the first image in this blog post, the hidden image is the ThinkFun logo! Can you see it now?

White’s Illusion

Can the same color look like two different colors within one image? White’s Illusion demonstrates that the answer is: yes! Our perception of brightness is influenced by the context in which the color occurs. When an object is surrounded by darker colors or lighter colors, our brain will interpret the objet itself to also be darker or lighter. The two gray columns above are actually the exact same shade of gray. Don’t believe us? Test it here.

This optical illusion was designed by an 11th grade student. An Australian psychologist named Michael White found the design in an optical art book and was determined to learn why the two columns appear to be different shades when they were in fact, the same. Although it’s been nearly 40 years, there is still no definitive answer. One theory is that two stripes beside each other assimilate into the surrounding stripes causing them to appear darker or brighter. Another theory suggests that the gray bars may appear to lie in front of or behind the surrounding stripes, giving the illusion that bars are slightly transparent and altered by the surrounding stripes. Since its discovery, other colors have also been applied to this illusion.

Illusory Motion

Does the stationary image above appear to be moving?

“Rotating Snakes” has long puzzled scientists. Doctors Benjamin Backus and Ipek Oruc studied this image to understand how aspects of visual perception influence the perception of motion. What they concluded was that if a person focused on one part of the image, the movement stopped, however, the movement continued if a person was scanning the image. They also noticed that the snakes always appear to rotate in the same direction, depending on the order of their colors: black, blue, white and yellow. Because of this, Backus and Oruc concluded that the neurons in our brains fire at different rates when looking at images, and depending on where the image hits our retina and the progression of colors, the illusion of motion is created.

Neurological Institute researcher Susana Martinez-Conde stated that such findings “help us to understand the neural bases of motion perception, both in the normal brain and in patients with brain lesions that affect the perception of motion. This research could aid in the design of neural prosthetics for patients with brain damage.”

Fraser Spiral Illusion

The original name of the illusion below is the “False Spiral.” Can you see why?

This illusion got its most recent name after being studied by psychologist James Fraser in 1908. This spiral above is not a spiral at all, but an image made of concentric circles. Look closely and you’ll notice that every ring in this illusion is its own enclosed circle. The circles themselves appear to be made of twisted cords, which lie in front of a checkered background. The brain processes this information and interprets the diagonal bands as a continuous line, giving rise to a false spiral.

Having trouble spotting the individual circles? Place your cursor over the image here.

Not all optical illusions are fully understood, but they help us understand how our brain processes information, and how those processes help us navigate through the world.

To learn about ThinkFun’s very own optical illusion Thinky the Dragon, check out our video!